A Comprehensive Guide to SPF Flattening

What is lookup in SPF record?

Lookups in an SPF (Sender Policy Framework) record refer to the DNS queries performed to validate that an email is sent from an authorized mail server for a given domain. When an email is received, the receiving mail server checks the SPF record of the sender’s domain to determine if the sending server is authorized. This involves various types of DNS lookups defined in the SPF record.

Here are the main types of lookups in an SPF record:

Limitation of SPF Lookups?

SPF lookups are limited to a maximum of 10 DNS queries(including “a”, “Mx”, “include”, “redirect” modifier, “exist” mechanism) to prevent excessive DNS querying, which can lead to delays or permanent failures in email delivery. Overly complex SPF records with too many lookups can cause validation issues, so it’s essential to manage and optimize SPF records carefully.

You can use https://www.progist.net/tools/spf-lookup.html to check your SPF DNS lookup count.

How to overcome SPF lookup limitation?

To eliminate this challenge, ProDMARC platform offers SPF flattening feature, which will effectively compress the SPF record and bring down the included lookups to less than 10 lookups.

Let’s focus on SPF Flattening mechanism and process.

What is SPF Flattening?

SPF Flattening is the process of managing and simplifying SPF record by consolidating multiple domains/includes into minimum number of lookups. It follows the mechanism of IP replacing and bifurcation of all domains included in SPF record.

Why is Flattening SPF Records Important?

Flattened SPF assist domain owner to control SPF DNS lookups specified in RFC-defined limit of 10. Adherence to this restriction guarantees the effective operation of the SPF authentication system, minimizing the occurrence of unintended errors.

SPF Record Flattening Process:

  • Enable ‘Managed SPF’ before SPF flattening deployment.

Enabling Manage SPF is necessary to conduct SPF flattening. Progist will handle the management of customer’s SPF and carry out the flattening process.

  • Removal of SPF mechanisms

The SPF compression process involves removing “a”, “mx”, and “include” mechanisms to further reduce redundancy and minimize lookups.

  • Replacing all domains with IPs.

To streamline SPF records, SPF flattening involves resolving all domain names referenced in the SPF record to their corresponding IP addresses and then replacing the domain names with these IP addresses. This simplifies the SPF record by removing the need to perform DNS lookups for each domain, reducing the risk of exceeding the DNS lookup limit imposed by some email systems.

  • IP detection and addition process

SPF flattening incorporates an IP detection mechanism where the tool monitors for any changes in SMTP IP addresses. Upon successful detection of new IPs, the tool verifies the overall SPF record to ensure that the new IPs are listed and adhere to the following conditions.

  • If yes, the tool disregards these new alterations.
  • If not, the tool automatically includes the IPs in the SPF record and performs SPF flattening if necessary.
  • Simplifying SPF record

Flattening the SPF record leads to a more straightforward and streamlined authentication process, reducing the occurrence of error messages, and simplifying the overall SPF setup.


In summary, SPF flattening provides a streamlined approach to managing SPF records by replacing domain names with IP addresses. This simplification helps minimize errors and ensures that SPF records accurately reflect authorized email sources. By automatically detecting and updating SMTP IP changes, SPF flattening maintains the integrity of SPF records, contributing to enhanced email security and deliverability.

Simplify SPF Management and Ensure Email Deliverability

Managing complex SPF records with multiple lookups can be a challenge. ProDMARC’s  SPF flattening feature ensures your records stay compliant and efficient. With ProDMARC, you can also:

  • Gain insights into email authentication with detailed reporting.
  • Protect your domain reputation from email spoofing attempts.
  • Improve overall email security posture.

Ready to experience the benefits of ProDMARC? To schedule a free demo click here or call us at 9820116312 Today!